A wide variety of patients with rare genetic disorders are studied: 1)an unusual variant form of nonketotic hyperlucinemia, 2) we have evaluated several infants and young children with acute metabolic disease initially diagnosed as Reye syndrome but shown by us to be rare inborn errors 3) long-term study of the efficacy of hepatic transplantation in the hepatorenal form of tyrosinemia 4) evaluation of optimal therapy for the Cbl-C subgroup of patients with methylmalonic acidemia 4) phenylalamine challenge PKU.